/Engine/Source/Editor/BlueprintGraph/Classes/K2Node_CustomEvent.h
Discernible from the baseUK2Node_Event's bOverrideFunction field. This checks to see if thisUK2Node_CustomEventoverrides another CustomEvent declared in a parent blueprint.
True if this CustomEvent's name matches another CustomEvent's name, declared in a parent (false if not).
bool IsOverride() const